Dependence is characterized by the symptoms of tolerance (requiring more of a substance to elicit the same effects) and withdrawal (symptoms that manifest when the substance is absent from one’s system). It is possible, albeit unlikely, to have a physical dependence without being addicted. Addiction, also known as substance use disorder, is listed in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as a chronic, relapsing brain disorder. It is characterized by compulsively engaging in rewarding stimuli (e.g., drinking alcohol, abusing drugs, gambling, etc.) without regard for consequence. An individual with substance use disorder will prioritize satisfying his or her addiction cravings above all else. This is largely due to biochemical changes in the brain and central nervous system that have occurred as a result of chronic substance abuse.